The present invention relates to an actuator for an inhaler for administering medicament by inhalation and to an inhaler including the same.
EP-A0448204 discloses one such actuator for delivering metered doses of medicament from an aerosol canister which comprises a body which defines a chamber containing medicament in a propellant under pressure, a valve stem which extends axially from one end of the body and an internal metering valve which is normally biased to a closed position and opened to deliver a metered dose of medicament when the valve stem is depressed. This actuator comprises an elongate tubular member which is configured to receive the canister such that the bottom wall of the body of the canister extends therefrom so as to be depressable by a user, a mouthpiece for guiding medicament to the mouth of a user and a nozzle block for receiving the valve stem of the canister and delivering medicament from the canister into the mouthpiece.
Such actuators have been used successfully for some time, but do, however, require a user to be able to develop sufficient force to open the metering valve of the canister, which force corresponds principally to the spring force of the closure spring in the metering valve. Traditionally, the metering valves of aerosol canisters containing chlorofluorocarbon based formulations have required a closure spring with a spring force of about 20 N. However, the metering valves of aerosol canisters containing the more recent alternative propellants, such as hydrofluorocarbons, require closure springs with a much higher spring force, typically about 40 N.
As will be appreciated, the development of such forces is often difficult, particularly for paediatric and geriatric patients, where the distance between the force application points is considerable, in being necessarily greater than the height of the canister. In a standard actuator the distance between the force application points is at least 60 mm.
It is therefore an aim of the present invention to provide an actuator for an inhaler for delivering medicament by inhalation which is configured such that the actuating force can be applied by a user in a more ergonomically favourable manner.
Accordingly, the present invention provides an actuator for an inhaler for delivering medicament by inhalation, comprising: a housing for receiving a canister comprising a body which defines a chamber containing medicament and a valve stem which extends from the body; a nozzle block for receiving the valve stem of the canister; a mouthpiece for providing medicament from the nozzle block to the mouth of a user, and at least one actuating member for manual engagement by a user in applying a force to actuate the canister, wherein the at least one actuating member is disposed such that the actuating force is applied substantially laterally relative to the longitudinal axis of the canister and configured when being acted upon to cause relative movement of the body and the valve stem of the canister.
With this configuration, the distance between the force application points is considerably less than in a standard actuator; the diameter of a standard actuator being substantially less than the height. Indeed, the distance between the force application points can be reduced typically to about 30 mm. This configuration is particularly advantageous as, where the actuating force is applied between a finger, typically the index finger, and the thumb, the closer the spacing between the finger and the thumb the more easily the required force can be generated.
In a preferred embodiment the at least one actuating member is configured when being acted upon to move the body of the canister in relation to the valve stem of the canister.
Preferably, the at least one actuating member includes an outwardly-facing surface for manual engagement by a user and an- inwardly-facing surface which in use bears against a surface of the canister.
In a preferred embodiment the bearing surface of the canister is a junction between a bottom wall and a side wall of the body of the canister.
Preferably, the inwardly-facing surface of the at least one actuating member includes an inclined surface portion over which the bearing surface of the canister in use progressively slides.
In one embodiment the inclined surface portion of the inwardly-facing surface is a substantially planar surface.
Preferably, the inclined surface portion of the inwardly-facing surface encloses an acute angle of more than 45 degrees with the longitudinal axis of the canister.
More preferably, the inclined surface portion of the inwardly-facing surface encloses an acute angle of at least 60 degrees with the longitudinal axis of the canister.
With this configuration, the inclined surface portion of the inwardly-facing surface of the at least one actuating member acts by the inclined plane effect to apply an amplified force to the body of the canister relative to the force applied by the user to the at least one actuating member, thereby allowing a user to apply a lower force, albeit over a greater distance, to actuate the canister than would be required if the force were applied axially directly to the bottom wall of the body of the canister.
In another embodiment the inclined surface portion of the inwardly-facing surface of the at least one actuating member is a curved surface.
Preferably, the tangent of the inclined surface portion of the inwardly-facing surface encloses an acute angle of more than 45 degrees with the longitudinal axis of the canister.
More preferably, the tangent of the inclined surface portion of the inwardly-facing surface encloses an acute angle of at least 60 degrees with the longitudinal axis of the canister.
As mentioned above, this configuration acts by the inclined plane effect to apply an amplified force to the body of the canister relative to the force applied by the user to the at least one actuating member.
In a preferred embodiment the at least one actuating member is hinged.
Preferably, the outwardly-facing surface of the at least one actuating member extends a greater distance from the hinge than the inwardly-facing surface of the at least one actuating member.
With this configuration, the at least one actuating member acts by the lever effect to apply an amplified force to the body of the canister relative to the force applied by the user to the at least one actuating member, thereby, similarly to the inclined plane effect described hereinabove, allowing a user to apply a lower force to actuate the canister than would be required if the force were applied axially directly to the bottom wall of the body of the canister. It will be appreciated that a significant mechanical advantage would be achieved where the at least one actuating member is configured to embody both this lever effect and the above-described inclined plane effect.
Preferably, the actuator further comprises a cover member which comprises a body part which is movably mounted to the housing between a first position in which the mouthpiece is disposed therewithin and a second position in which the mouthpiece is exposed.
Preferably, the body part is rotatably mounted to the housing.
Preferably, the body part includes an opening through which the mouthpiece extends in the second position of the body part and the cover member further comprises a flap which is movably mounted to the body part between a first position in which the opening in the body part is closed and a second position in which the opening in the body part is open.
Preferably, the at least one actuating member is integral with the body part.
In a preferred embodiment the actuator comprises first and second actuating members.
Preferably, the actuating members are oppositely directed.
The present invention further provides an actuator for an inhaler for delivering medicament by inhalation, comprising: a housing for receiving a canister comprising a body which defines a chamber containing medicament and a valve stem which extends from the body; a nozzle block for receiving the valve stem of the canister; a mouthpiece for providing medicament from the nozzle block to the mouth of a user, and first and second actuating members for manual engagement by a user in applying a force to actuate the canister, wherein the actuating members are opposed and movably mounted relative to the housing.
The present invention also extends to inhalers comprising the above-described actuators and a canister containing medicament.